STATIC CHARGES CAN DISTROY YOR DCC CHIP!

[mkrob]

Have you ever had a static discharge  from your body make you jump?  Nobody seems to talk about ESD, where dcc is concerned. Are people not aware of it? Why do dcc decoders go wrong for no apparent reason. Does anyone use an Anti-Static Grounding Kit,when fitting their dcc decoders. I don't suppose many people are aware of it! The damage caused by static discharges can cause a component to fail immediately and also it can cause latent failures to occur which can manifest themselves later, considerably reducing the overall reliability of the product. Here's some info about it. Read it if you value your expensive sound decoder.

https://www.electronics-notes.com/articles/constructional_techniques/electrostatic-discharge/esd-effects-how-affects-electronics.php

[BrushVeteran]

That's thrown up an interesting memory from the 1980's when I was working for Oxford Bus Company. We had some buses arrive with an early form of electronic destination indicator called Transdot and all the route information was encoded into an eprom which was mounted on a circuit board together with other eproms which operated the roll over system. To fit these eproms we were always told to wear hand straps fitted with crocodile clips which earthed the eprom whilst you were handling it. It has never occurred to me that a decoder is the modern equivalent of an eprom but it would make perfect sense to use a handstrap when handling a decoder. I would of thought that wearing of protective gloves would also be an adequate shield from body static charge. I've never really understood how static charge builds up in your body/clothing but remember my old Austin Maxi had to be fitted with an earth strap as it was good for giving me a 'belt' off the door handles..............the only car that I ever had this problem with. If it is just our clothing which causes the static i.e. nylon.......used to be told that this could be the cause........ then we'll all have to get used to taking our clothes off when fitting decoders.................now that's an interesting thought!

[RobinofLoxley]

Or simply clap your hands before starting.

 

And dont wear a fleece.

[Mick Bonwick]

1 hour ago, RobinofLoxley said:

Or simply clap your hands before starting.

 

And dont wear a fleece.

 

How do sheep manage, then?

[H2O]

Static electricity will easily kill semiconductor devices when they are on their own, but once soldered or plugged in to a pcb the risk is greatly reduced. Hence an EEPROM is vulnerable before being plugged into a socket but very much safer once inserted.

If handling electronics it is a good idea to 'ground' yourself before working on sensitive parts by touching something that is grounded but once a decoder is installed you should be ok.  A dcc decoder (installed or not) should be no more vulnerable than an Arduino or Raspberry micro board.

Even when correctly installed a dcc decoder is operating in a fairly harsh envirnment controlling a dc motor on what can be an intermittent power supply.  When a motor turns off it can generate high voltages.  These are normally handled by using protection diodes.

Semiconductor components not soldered in to a circuit could include a MOSFET which only has 3 leads.

[doilum]

And don't stroke the cat......

Edited February 22, 2021 by doilum
Predictive text error

[Oldddudders]

16 hours ago, Mick Bonwick said:

 

How do sheep manage, then?

In my observation they are fairly static anyway....

 

One advantage of Continental plugs and sockets is that while the UK has an earth pin on the plug, here the earth pin sticks out from the socket, so croc-clipping yourself to earth is quite easy. It certainly worked last year when I upgraded the storage in a MacBook Air from 128GB to 480GB. I think I bought the wrist-strap some years ago when upgrading the QSI sound chips in some US HO locos. 

[cypherman]

The easiest way to get rid of a static charge is just touch a radiator bleed cap for a couple of seconds. Static charge destroying microchips has been known about in computers for at least the last 30 years. DCC chip is just another type of computer chip. It is also not a good idea to be working on electronics while standing on man made carpets such as nylon. Wearing rubber soled shoes also helps stop the build up of static. But you still need to discharge yourself against something like a radiator. But I must in the 40+ years I have been building and upgrading computers I have not had a problem with this. But then again I have always taken precautions. Could this be famous last words......

[kevinlms]

2 hours ago, doilum said:

And don't stroke the cat......

With an ebonite rod!

[Il Grifone]

On 22/02/2021 at 11:00, Oldddudders said:

In my observation they are fairly static anyway....

 

One advantage of Continental plugs and sockets is that while the UK has an earth pin on the plug, here the earth pin sticks out from the socket, so croc-clipping yourself to earth is quite easy. It certainly worked last year when I upgraded the storage in a MacBook Air from 128GB to 480GB. I think I bought the wrist-strap some years ago when upgrading the QSI sound chips in some US HO locos. 

 

A French speciality I'm afraid. Italian plugs have three pins in line, though these days everything seems to come equipped with a German Schuco plug, later versions of which have a socket for the French earth pin.

I have made a few earthing plugs with just a green/yellow lead to the earth pin (ENSURE it is the earth pin!). These can be used for static earthing. I have never had problems with static, but better safe than sorry.

I find it is necessary to earth Hi-Fi equipment and they also serve here. Invariably these have twin core mains lead (to prevent hum through multiple earth connections) and the metal-work feels 'live' when touched*. Allergic to this, I always earth the system. One earth only - to the amplifier or to the record deck if you still use vinyl.

Back to model railways, earthing the common return avoids a similar effect with the rails and helps to reduce interference.

 

*A shock is not unknown....

[Dagworth]

3 minutes ago, Il Grifone said:

Back to model railways, earthing the common return avoids a similar effect with the rails and helps to reduce interference.

and may well upset your DCC system. I know that if I try to solder on the rails with my Lenz set 100 connected it will cut out. 
 

Andi

[Il Grifone]

I wouldn't have thought that even DCC wiring would be upset by earthing one side of the system. However it would depend on the circuit of the supply.